A light-hearted series that might appeal to a younger reader is The Gallagher Girls series by Ally Carter. The first book in the series is "I'd Tell You I Love You, But Then I'd Have to Kill You." This is a story about the The Gallagher Academy for Exceptional Young Women. It is an exclusive finishing school for young women, but there is a twist because these young women are being trained to be spies. Lots of fun and excitement as the girls get into their share of trouble as they solve mysteries.
Another favorite of not only myself, but lots of YA readers is The Hunger Games series by Suzanne Collins. This series is an I-can't-put-it-down type of read. Katniss Everdeen volunteers to be sent into the hunger games in place of her sister. The hunger games is a game where twenty-four go in but only one comes out. This series has the third book, Mockingjay, coming out in theaters this November.
Another Dystopian series is Matched by Ally Condie. This is a story where your perfect match is decided for you. So, what happens when the matching process gets manipulated and the one chosen for you is not the perfect one. This is a story about choice and love.
With the reports of human trafficking in the news, this series will make you think. Wither is written by Lauren Destefano. Science, while searching for perfection, has created a world where young people only live to their early twenty's. This makes the need to reproduce vital to the existence of humanity. A very interesting series as the reader wonders where love and choice fit into the story.
I'll finish back on a lighter note with How to Ruin a Summer Vacation by Simone Elkeles. This is a series about a teenage girl who is learning about herself and her heritage and getting stronger because of it. She's not excited when her father decides it's time for her to spend a summer with her grandmother in Israel. It has ruined all of her summer plans, but it opens up the world for her. This was a very fun book.
So that is just a tip-of-the-iceberg of YA series. I hope you have found some favorites that have you anxiously awaiting the next one in the series.